How much of a country's emissions are down to the way its people live? Countries like China and India may be among the world's worst CO2 emitters - but a great many of their citizens' carbon footprints are very small. Use the links below to meet ordinary families in the USA, UK, United Arab Emirates, India and China and get a glimpse of their carbon lives.
THE MADDEN FAMILY, FROM THE USA
"I think everyone needs to do their bit - but in America we use an awful lot" - Valerie Madden.
Matthew Price went to Boston, Massachusetts, to meet the Madden family. Ben is a computer engineer, his wife, Valerie, is a hospital admin assistant. They have two children, Henry, three and Sophia, nine.
THE CAPP FAMILY, FROM THE UK
"I do go around, constantly telling the children - 'please switch that off'!" - Alison Capp.
The Capp family live in Minster, Kent.
Dad Paul is a teacher and mum Alison works for a foster care agency.
Nick Higham met them - and their children Jennifer, nine, Oliver, 11 and Hannah, 18.
THE SAAD FAMILY, FROM THE UNITED ARAB EMIRATES
"I'm scared about the future... but to be honest I don't change my lifestyle" - Mohsen Saad.
"I do worry about the petrol bills - but it's cheaper in this country than anywhere else" - Rania Saad.
Roger Harrabin went to the United Arab Emirates to meet Rania and Mohsen Saad.
The couple are both academics and have a young daughter, Clara.
THE KAMRA FAMILY, FROM INDIA
"There is no way of comparing India to America" - Pawan Kamra.
Sanjoy Majumder visited Pawan and Sangeeta Kamra at their home in south Delhi.
Pawan is an office manager and Sangeeta is a housewife.
They have two children: Prathmesh, four, and Tulika, three months.
HUANG WEIQUN AND CAI YUWEI, FROM CHINA
"We hardly use any energy!" - Huang Weiqun
Huang Weiqun and her son Cai Yuwei, 18, live in Shanghai. Huang works as a cleaner.
They live in a one-bedroomed apartment and use a kitchen shared by 11 others.
Quentin Sommerville went to meet them.